Philippine President Gloria Arroyo has temporarily moved the army headquarters to the south of the country, to boost operations against Islamist militants.

"I have ordered army commanding general Romeo Tolentino to the front lines," Mrs Arroyo said in a statement.

"The army headquarters will now be temporarily set up in Zamboanga until the situation normalises."

Fighting on Jolo island this week has left at least 50 people dead, 25 of them soldiers killed in a single day.

Following the clashes thousands of civilians have fled their homes on the island, which is some 950km (600 miles) south of the capital, Manila.

The new Defence Secretary, Gilbert Teodoro, Lt-Gen Romeo Tolentino and another top official, Gen Hermogenes Esperon, visited Jolo on Sunday, where an extra 1,000 soldiers have joined 4,000 already stationed there.